Last week it was claimed that, among his 99 other problems, Jay-Z may have been lying about his age.

According to New York DJ Troi Torain aka 'Star' the global superstar, real name Shawn Corey Carter, is a 50-year-old, not 44 as has been traditionally reported.

"I shouldn't blow this up, maybe because he doesn't promote it publicly, but Jay-Z and I are the same age," Lifestylemag reported shock jock Torain saying. "I will be 50 on May 3. He's 43, 42. That's just media made."

If Torain's (as yet unsubstantiated) allegations do turn out to be true – and they might well not be, the DJ has form for making outrageous claims – then the rapper certainly wouldn't be the first to have tweaked his age.

In 1999 Eminem told radio DJ Howard Stern he was 24 when in fact he was 27, Nelly was revealed to have been 28 when Teen People nominated him as one of its '25 Hottest Stars Under 25' and singer Anastasia was actually 30 when she signed to a record deal, not in her 20s as claimed.

She explained in one interview: "They suggested I say I was 24 and I went with it ... I spent 10 years lying about my age."

You only have to watch the desperation of those in the 'overs' category on any given series of the X-Factor, tearfully insisting this is their 'last chance at stardom', to understand why a performer might be tempted to shave a few years off their real age.

The music industry can be cruel when it comes to age. Robbie Williams (40) was said to be 'gutted' after Radio One decided not to play his new single and DJ Nick Grimshaw branded him 'irrelevant' to the station's target audience.

Even seasoned performers bringing in big crowds don't escape negative quips made about their age, like last year when one newspaper ran a story on Mick Jagger (70) and Keith Richards (70) at Glastonbury headlined 'Night of the Living Dead'.

Interestingly, research by the Recording Industry Association of America shows that it's actually the 45 plus age group who buy most music, but because it's the younger listeners who are more likely to buy merchandise and support a debut act, the gate keepers of pop culture – the labels and radio stations – can tend to see aging as a turn off.

The worrying thing is that this fear of one's true age then filters down into everyday life.

"On a professional level I can tell you that aging comes up in therapy frequently, how can it not when we are all being bombarded with messages to fear what is inevitable?" says Cork-based counselling psychologist and psychotherapist Sally O'Reilly (sallyoreilly.com)

"Youth is the home of all things sexy, active and interesting. Every day we're told age is important, with adverts telling us that we might not 'need' botox 'yet' if we use X brand of 'youth serum'.

"We're learning that to look older than teenagers is a very bad thing and so we lie about our age."

In an era dominated by looking and being young, anyone over a certain age – perhaps even a multi-millionaire rap star – can start to feel redundant.

"People often say 50 is the new 30 but they wouldn't say that if they listened to the 50-year-olds who have been told that they are unemployable," says Ciaran McKinney, spokesman for Age and Opportunity (ageandopportunity.ie).

Since most of us aren't trying to woo a young fan base, the reason why many people lie about age comes down to fear.

"As a society we're living older and with that has come more age-related disease like dementia and Alzheimers – these are things we've grown to fear rather than accept," explains Sally.

"Studies are consistently showing that we fear being dependent on younger relatives now, we fear losing our memory, our physical abilities. These weren't major concerns a century ago, we just weren't living long enough, and there wasn't such an emphasis on the perceived value of youth."

The more aging is portrayed in a negative way in the media, the more negative attitudes to aging thrive.

Ciaran explains: "Ageism at a cultural level leads us all to have lower expectations of ourselves as we age.

"Wouldn't it be better if we were encouraged to achieve our full potential no matter what our age?"